Speaking ahead of the release of a new BBC documentary marking 25 years since 18-year-old Lawrence was stabbed to death in a racist attack in London, Imran Khan QC said the film reveals progress on racism is “simply lip service”.

“We had a number of police officers who I had assumed had moved forward with us, but having viewed the programmes, I feel betrayed by those officers,” the human rights lawyer said.

Speaking at a screening in London, former Detective Chief Inspector Clive Driscoll, who finally secured two convictions for Lawrence’s murder in 2011, said it was vital for police to win back the confidence of black communities in order to tackle the wave of gun and knife crime that has gripped London in recent weeks.

“If you don’t feel that the [police] agency is designed to protect you, who are you going to turn to?,” Driscoll said.

“There needs to be a full range of tactics to try and win back people who think ‘I’m going to carry a knife, because you’re not going to help me’.”

BBCStephen Lawrence was killed 25 years ago in a racially motivated attack in south-east London

The Lawrence case was a turning point in race relations in the UK, with failures in the police investigation prompting a profound breakdown in trust between the UK’s black community and the police.

Due to errors in the investigation, the teenager’s parents, Doreen and Neville Lawrence, were forced to launch the first private murder prosecution in 150 years after his killers walked free due to a lack of evidence.

A 1999 investigation into the Met’s handling of the case, called the Macpherson report, determined that Scotland Yard was institutionally racist and had made a series of mistakes during the investigation.

The three-part documentary ‘Stephen: The Murder that Changed a Nation’, which airs on April 17, features interviews with a number of police officers involved in the murder probe.

Khan said the interviews expose the fact that a wider desire to tackle racism in the Met Police has not been fully accepted by the force.

“I think now [institutional racism] is hidden far better than it was, but it exists and it is thriving and there is a lot more that we have got to do,” Khan explained.

“Having seen the documentary, I have got angry all over again because I realised that it was an awful process that the family had to go through and it’s still happening.”

BBCDCI Clive Driscoll said the Met must come down on discrimination within the force 'like a tonne of bricks'

Khan added: “I want to reignite that anger and hold the Met to account again, because I think we are being fed a lie that things have changed.”

Driscoll claimed that institutional racism had been ongoing for a “very, very long time”.

“The police need to focus very carefully on making sure they are open and transparent. They say it a lot – they need to make sure they are,” he said.

“If they do come across any kind of discriminatory behaviour they need to come down on it like a tonne of bricks, otherwise nobody will have any confidence in the system or the police and that makes policing harder.”

A spokesperson for the Met Police told HuffPost UK:

“The Metropolitan Police Service has not yet viewed the BBC Documentary filmed for the 25th Anniversary of the death of Stephen Lawrence and so cannot comment on its specific contents.

“Stephen’s horrific murder was a terrible act. The Public Inquiry, published in 1999, made a series of recommendations which led to far-reaching changes in the Met’s approach to murder investigation, race crime and staff diversity. The Met has brought two people to justice for this appalling crime.

“The Commissioner has been instrumental in personally improving the response to racist crime in London and enhancing the service we give to London’s black community. She has very clearly stated she will not tolerate racism within the MPS. Our high standards and expectations are made clear when officers and staff join the MPS, and are reinforced during training throughout their careers. The MPS has a clear set of values for its staff and the code of ethics reinforces the standards of behaviour expected.

“The Metropolitan Police Service employs over 40,000 people who engage with the public millions of times each year. The overwhelming majority of those contacts are carried out with professionalism and courtesy. In the small amount of cases when this is not the case, the Directorate of Professional Standards carries out a thorough investigation to ascertain the facts of the interaction and where necessary instigate misconduct proceedings. Our officers’ response, when a small minority of their colleagues are found to be guilty of racist behaviour, can leave others in no doubt that there is no place for racism within the MPS.”

The first episode of ‘Stephen: The Murder that Changed a Nation’ will be broadcast on BBC One on April 17 at 9pm.